This invention relates to a color image processing apparatus and, more particularly, to a color image processing apparatus characterized by its color reproduction processing.
A method of color reproduction processing by a conventional digital color image copying apparatus using electrostatic photography or ink-jet printing includes color processing in which a color image output signal is obtained by referring to a table memory storing corresponding relationships for converting quantized color image signals of the colors red (R), green (G) and blue (B) into output printing signals of the colors cyan (C), magenta (M) and yellow (Y), respectively.
However, mn the conventional method of reproducing colors mentioned above, the following problems arise:
(1) The method requires the provision of the aforementioned table memory, which is the equivalent of color processing for applying a masking operation to RGB density signals Dr, Dg, Db consisting of eight bits per color, and obtaining Y, M, C, K output signals also consisting of eight bits per color. As a consequence, a large memory capacity is required and cost is high.
(2) Quantizing the memory input signal and reducing memory capacity means reducing the tone quality of the read image signal. As a result, the tone quality of the output image is eliminated and a false contour is produced, thereby greatly detracting from picture quality.
(3) Reducing memory capacity while maintaining tone quality in an effort to solve the foregoing problems involves narrowing the reproduction range of the read image signal. This results in greatly diminished picture quality, such as deterioration of the output image at portions where saturation is high.